The present invention relates to bearings and in particular relates to bearings for translational slideway systems. In one embodiment the invention relates to gas bearings for such systems.
In mounting machine parts to slide on gas bearings it is often required to provide bearing surfaces between the parts which will restrain movement of the machine parts in two orthogonal directions.
In the past it has been common to provide two air bearing surfaces at right angles on one part with confronting air bearing surfaces on the other part to form a vee guide. It is important for the relative alignment of the two orthogonal surfaces to be extremely accurate in order that the very small clearances required for proper operation of the air bearing are not adversely affected by relative misalignment of the surfaces. This is difficult to achieve in practice and results in costly machining operations, and/or the provision of some form of articulation to enable self-alignment to take place.
Also it is known to provide an air bearing in the form of a hollow cylinder mounted for movement along a cylindrical guideway. Such bearings, however, are not practical in a machine, for example a measuring machine, having long guideways since the guideway can only be supported at its ends, and it is difficult under such circumstances to ensure adequate stiffness of the guideway to maintain measurement accuracy.